Extraosseous Ewing sarcoma and peripheral primitive neuroectodermal tumor of the thyroid gland: Case report and review.

The Ewing family of tumors and peripheral primitive neuroectodermal tumor (pPNET) represent different manifestations of the same entity. Immunohistochemical and cytogenetic studies suggest that these tumors have a common origin. Ewing sarcoma is more common in bone, while pPNET is more common in soft tissues. Extraosseous Ewing sarcoma (EoES) is rare. We present the case of a 48-year-old man who presented with acute obstructive respiratory failure secondary to a large thyroid swelling. The patient was initially diagnosed with giant B-cell non-Hodgkin lymphoma and treated with chemotherapy. However, subsequent immunohistochemical staining of biopsy specimens revealed that the patient actually had EoES/pPNET of the thyroid gland. We performed a nearly complete surgical resection of the tumor plus a total laryngectomy and resection of five tracheal rings. However, the patient died of a cerebral metastasis 1 month later after he had completed one cycle of postoperative chemotherapy.